Puget Sound/ˈpjuːdʒɪt/ is a sound along the northwestern coast of the U.S. state of Washington, an inlet of the Pacific Ocean, and part of the Salish Sea. It is a complex estuarine[3] system of interconnected marine waterways and basins, with one major and one minor connection to the open Pacific Ocean via the Strait of Juan de Fuca—Admiralty Inlet being the major connection and Deception Pass being the minor. Flow through Deception Pass is approximately equal to 2% of the total tidal exchange between Puget Sound and the Strait of Juan de Fuca.[1] Puget Sound extends approximately 100 miles (160 km) from Deception Pass in the north to Olympia, Washington in the south. Its average depth is 450 feet (140 m)[4] and its maximum depth, off Point Jefferson between Indianola and Kingston, is 930 feet (280 m). The depth of the main basin, between the southern tip of Whidbey Island and Tacoma, Washington, is approximately 600 feet (180 m).[1]

The term "Puget Sound" is used not just for the body of water but also the Puget Sound region centered on the sound.

Another definition, given by NOAA, subdivides Puget Sound into five basins or regions. Four of these correspond to areas within the USGS definition, but the fifth one, called "Northern Puget Sound" includes a large additional region. It is defined as bounded to the north by the international boundary with Canada, and to the west by a line running north from the mouth of the Sekiu River on the Olympic Peninsula.[7] Under this definition significant parts of the Strait of Juan de Fuca and the Strait of Georgia are included in Puget Sound, with the international boundary marking an abrupt and hydrologically arbitrary limit.

According to Arthur Kruckeberg, the term "Puget Sound" is sometimes used for waters north of Admiralty Inlet and Deception Pass, especially for areas along the north coast of Washington and the San Juan Islands, essentially equivalent to NOAA's "Northern Puget Sound" subdivision described above. Kruckeberg uses the term "Puget Sound and adjacent waters".[8]

An alternative term for Puget Sound, still used by some Native Americans and environmental groups, is Whulge (or Whulj), an Anglicization of the Lushootseed name 'WulcH, which means "Salt Water".[9] Since 2009 the term Salish Sea has been established by the United States Board on Geographic Names as the collective waters of Puget Sound, the Strait of Juan de Fuca, and the Strait of Georgia. Sometimes the terms "Puget Sound" and "Puget Sound and adjacent waters" are used for not only Puget Sound proper but also for waters to the north, such as Bellingham Bay and the San Juan Islands region.[8]

Continental ice sheets have repeatedly advanced and retreated from the Puget Sound region. The most recent glacial period, called the Fraser Glaciation, had three phases, or stades. During the third, or Vashon Glaciation, a lobe of the Cordilleran Ice Sheet, called the Puget Lobe, spread south about 15,000 years ago, covering the Puget Sound region with an ice sheet about 3,000 feet (910 m) thick near Seattle, and nearly 6,000 feet (1,800 m) at the present Canada-US border. Since each new advance and retreat of ice erodes away much of the evidence of previous ice ages, the most recent Vashon phase has left the clearest imprint on the land. At its maximum extent the Vashon ice sheet extended south of Olympia to near Tenino, and covered the lowlands between the Olympic and Cascade mountain range. About 14,000 years ago the ice began to retreat. By 11,000 years ago it survived only north of the Canadian border.[10]

The melting retreat of the Vashon Glaciation eroded the land, creating a drumlin field of hundreds of aligned drumlin hills. Lake Washington and Lake Sammamish (which are ribbon lakes), Hood Canal, and the main Puget Sound basin were altered by glacial forces. These glacial forces are not specifically "carving", as in cutting into the landscape via the mechanics of ice/glaciers, but rather eroding the landscape from melt water of the Vashon Glacier creating the drumlin field. As the ice retreated, vast amounts of glacial till were deposited throughout the Puget Sound region.[1] The soils of the region, less than ten thousand years old, are still characterized as immature.

As the Vashon glacier receded a series of proglacial lakes formed, filling the main trough of Puget Sound and inundating the southern lowlands. Glacial Lake Russell was the first such large recessional lake. From the vicinity of Seattle in the north the lake extended south to the Black Hills, where it drained south into the Chehalis River.[11] Sediments from Lake Russell form the blue-gray clay identified as the Lawton Clay. The second major recessional lake was Glacial Lake Bretz. It also drained to the Chehalis River until the Chimacum Valley, in the northeast Olympic Peninsula, melted, allowing the lake's water to rapidly drain north into the marine waters of the Strait of Juan de Fuca, which was rising as the ice sheet retreated.[11]

Puget Sound is a large salt water estuary, or system of many estuaries, fed by highly seasonal freshwater from the Olympic and Cascade Mountain watersheds. The mean annual river discharge into Puget Sound is 41,000 cubic feet per second (1,200 m3/s), with a monthly average maximum of about 367,000 cubic feet per second (10,400 m3/s) and minimum of about 14,000 cubic feet per second (400 m3/s). Puget Sound's shoreline is 1,332 miles (2,144 km) long, encompassing a water area of 1,020 square miles (2,600 km2) and a total volume of 26.5 cubic miles (110 km3) at mean high water. The average volume of water flowing in and out of Puget Sound during each tide is 1.26 cubic miles (5.3 km3). The maximum tidal currents, in the range of 9 to 10 knots, occurs at Deception Pass.[1]

The Puget Sound system consists of four deep basins connected by shallower sills. The four basins are Hood Canal, west of the Kitsap Peninsula, Whidbey Basin, east of Whidbey Island, South Sound, south of the Tacoma Narrows, and the Main Basin, which is further subdivided into Admiralty Inlet and the Central Basin.[15] Puget Sound's sills, a kind of submarine terminal moraine, separate the basins from one another, and Puget Sound from the Strait of Juan de Fuca. Three sills are particularly significant—the one at Admiralty Inlet which checks the flow of water between the Strait of Juan de Fuca and Puget sound, the one at the entrance to Hood Canal (about 175 ft or 53 m below the surface), and the one at the Tacoma Narrows (about 145 ft or 44 m). Other sills that present less of a barrier include the ones at Blake Island, Agate Pass, Rich Passage, and Hammersley Inlet.[8]

The size of Puget Sound's watershed is 12,138 sq mi (31,440 km2).[2] "Northern Puget Sound" is frequently considered part of the Puget Sound watershed, which enlarges its size to 13,700 sq mi (35,000 km2).[16] The USGS uses the name "Puget Sound" for its hydrologic unit subregion 1711, which includes areas draining to the Puget Sound proper as well as the Strait of Juan de Fuca, the Strait of Georgia, and the Fraser River.[17] Significant rivers that drain to "Northern Puget Sound" include the Nooksack, Dungeness, and Elwha Rivers. The Nooksack empties into Bellingham Bay, the Dungeness and Elwha into the Strait of Juan de Fuca. The Chilliwack River flows north to the Fraser River in Canada.

Tides in Puget Sound are of the mixed type with two high and two low tides each tidal day. These are called Higher High Water (HHW), Lower Low Water (LLW), Lower High Water (LHW), and Higher Low Water (HLW). The configuration of basins, sills, and interconnections cause the tidal range to increase within Puget Sound. The difference in height between the Higher High Water and the Lower Low Water averages about 8.3 feet (2.5 m) at Port Townsend on Admiralty Inlet, but increases to about 14.4 feet (4.4 m) at Olympia, the southern end of Puget Sound.[1]

Among the marine mammals species found in Puget Sound are harbor seals (Phoca vitulina).[22]Orca (Orcinus orca) are famous throughout the Sound, and are a large tourist attraction. Although orca are sometimes seen in Puget Sound proper they are far more prevalent around the San Juan Islands north of Puget Sound.[23]

After 1818 Britain and the United States, which both claimed the Oregon Country, agreed to "joint occupancy", deferring resolution of the Oregon boundary dispute until the 1846 Oregon Treaty. Puget Sound was part of the disputed region until 1846, after which it became US territory.

The first American settlement on Puget Sound was Tumwater. It was founded in 1845 by Americans who had come via the Oregon Trail. The decision to settle north of the Columbia River was made in part because one of the settlers, George Washington Bush, was considered black and the Provisional Government of Oregon banned the residency of mulattoes but did not actively enforce the restriction north of the river.[39]

A unique state-run ferry system, the Washington State Ferries, connects the larger islands to the Washington mainland, as well as both sides of the sound, allowing people and cars to move about the greater Puget Sound region.

In the past 30 years there has been a large recession in the populations of the species which inhabit the Puget Sound. The decrease has been seen in the populations of: forage fish, salmonids, bottom fish, marine birds, harbor porpoise and orcas. This decline is attributed to the various environmental issues in Puget Sound.[citation needed] Because of this population decline, there have been changes to the fishery practices, and an increase in petitioning to add species to the Endangered Species Act. There has also been an increase in recovery and management plans for many different area species.[42]

The causes of these environmental issues are toxic contamination, eutrophication (low oxygen due to excess nutrients), and near shore habitat changes.[42]

The Puget Sound is mentioned in multiple songs including "Hello Seattle" by Owl City, "This Place is a Prison" by The Postal Service, "Volcano" by The Presidents of the United States of America and "Frances Farmer Will Have Her Revenge On Seattle" by Nirvana among others.[43]

Snow Falling on Cedars, by David Guterson, is set on the fictional San Piedro Island in the northern Puget Sound region of the state of Washington coast in 1954.

Prosser, William Farrand (1903). A history of the Puget Sound country : its resources, its commerce and its people : with some reference to discoveries and explorations in North America from the time of Christopher Columbus down to that of George Vancouver in 1792, when the beauty, richness and vast commercial advantages of this region were first made known to the world. Lewis Pub. Co.Available online through the Washington State Library's Classics in Washington History collection